Process of removing sulfureted hydrogen from gases.



K. BURKHEISER.

PROCESS OF REMOVING SULFURETED HYDROGEN FROM GASES.

APPLICATION FILED MAR. 2. 1914.

L31, 875, Patented Nov. 16, 1915.

H 5 Fun ficoflbn Su/fur Exfmcf/im Separa for Air fiegeneraflon A if Ifiegenera hon WITNESSES //v l/E/V TOR 496M 771a M Y KARL BUBRHEISEB, 01FFRUCH'I' HOF, HAMBURG, GER MANY.

PROCESS OF REMOVING SULFURETED HYDROGEN FROM GASIIIS.

Toall whom it may cofwern:

Be it known that I, KARL Bunxnmsnn, a subject of the Emperor of Germany,residing at Fruchthof, Ecke Banksstrasse, Hamburg, Germany, haveinvented certain new and useful Improvements in Processes of RemovingSulfureted Hydrogen from Gases; and I do hereby declare the following tobe a full, clean-and exact description of the invention, such as willenable others skilled 1 in the art to which it appertains to make anduse. the same.

In an application for Letters Patent of the United States, Serial No.713750, filed July 8, 1912, I have described a process wherein gascontaining sulfureted hydrogen is washed with an alkaline emulsion ofmetal oxid or hydrated metal oxid for the purpose of removing thesulfureted hydrogen. In operatingcontinuously, the mode of procedure issuch that, for instance, hydrated iron oxid is emulsified in a waterysolution of ammonia and is conducted through a washing apparatus in adirection opposed to the gas current, containing sulfureted hydrogen.The ammonia in suspension removes the sulfureted hydrogen of the gas,with the formation of ammonium sulfid. The hy-- drated iron oxidcontained at the same time in the ammonia solution regenerates theammonium sulfid solution with the formation of iron sulfid and freeammonia solution whichis thereupon utilized again anew for:

the absorption of sulfureted hydrogen from the gas current. I

After all of the hydrated iron oxid is converted into iron sulfurcompounds, the emulsion leaves the sulfureted hydrogen purificationapparatus and is separated in a further special apparatus into liquidand iron sulfur compounds. The iron sulfur compounds are oxidized up tothe formation of sulfurous acid and the residual hydrated iron oxid,

emulsified with the ammonia solution not otherwise emploved or withfresh ammon'ia solution, is again delivered to the sulfureted' hydrogenpurification apparatus.

If now the gas, as frequently happens contains oxygen, a regeneration ofthe 1ron sulfur compounds to hydrated oxid of iron and free sulfur takesplace at the same time in the sulfureted hydrogen purification apparatusand principally where the hydrated iron oxid is alreadv almostcompletely converted into iron sulfur compounds. The

ammonium sulfid now acts upon the sulfur produced by theoxygen contentof the gas from the iron sulfur compounds, with the 1 formation ofammonium polysulfids, so that. much more sulfureted hydrogen can be re-.converted into, ammonium polvsulfid solution and must be removedtherefrom.

The present invention is based upon the conception vto extendthisconversion of a part \only of the sulfur into dissolved sulfur toall of the sulfur, and to thus recover all of the sulfur as dissolvedsulfur in a uniform manner and to build up the entire process in all ofits parts as a cyclic process wherein there never occurs an accumulationor a deficit in reaction products. The most obvious way would be to mixwith the gases so much oxygen that all of the iron sulfur compounds beregenerated in the sulfureted hydrogen purification apparatus itself sothat there would always be bound all of the sulfur as ammoniumpolysulfids. Inasmuch,

however, as the gas cannot be mixed with so much oxygen and also becausethe ammonium polysulfid reacts exactly as ammonium sulfid with thehydrated iron oxid, with the formation of iron sulfur compounds, aconversion of all of the sulfur into soluble sulfur in this way is notpossible. A similarly obvious way of subjecting the metal sulfidsleaving the purifier to the customary oxidation so that they may consistof metal oxid and free sulfur and to'extract said sulfur withalkalisulfid, similar to Specification of Letters Patent. Patented N 0%16, 1915. I

Application sled March 2, 1914. Serial no. senses.

what has been repeatedly proposed for other i V sulfur extraction media,such as carbon bisulfid, etc., is not feasible because not only thealkali sulfid, but also the alkali polysulfids react with the admixedhydrated iron oxid and each molecule of hydrated iron oxid requiresthree molecules of alkali sulfid for its saturation. Thus, not only isthe greater part of the alkali sulfid withdrawn in any event'from thedissolving process but the mass must also be subjected to a specialtreatment for a renewed desulfurization with another sulfur dissolvingmedium, as otherwise, in continuous working, an uninterruptedaccumulation of sulfur would take place in the mass.

I"he invention therefore contemplates excluding the action of the alkalisulfid upon of alkali sulfid, and then effecting a separation of theliquids and the solid portions. These solid portions will then consistonly of iron sulfur compounds, which, for their part, are oxidized tohydrated oxid of iron and sulfur and therefore give the same mixturewhich has served as the initial material for the gas purification andwhich consequently can be employed anew for gas purification, so that acomplete cyclic process results. The sulfur is removed by the alkalisulfid from the circulation of the purifying mass in the .form of alkalipolysulfid and is removed therefrom in any suitable way. The alkalisulfid is, in this case, solely a dissolving medium and does not enterinto any other combinations. Hence,

the alkali sulfid is recovered, and, after the removal of the sulfurdissolved therein is available anew as a solvent, so that a second cycleresults and a removal of the sulfur from the gas takes place.Furthermore, since all of the reaction products themselves result fromthe gas purifying operation itself, and are continuously produced anewin the carrying out of the two cyclic processes, the method isextraordinarily economical and can be incorporated at once into the gaspurification process itself, so that any special adaptation issuperfluous.

The invention further extends to the employment of the ammonia containedin the gas itself, instead of a special alkali, since the removal of thesulfureted hydrogen is undertaken immediately after the removal of thetar, 2'. e., the sulfureted hydrogen purification is undertaken whilethe gas still contains its ammonia. The use of a special alkali istherefore superfluous, because,- as has been said, the ammonia contained in the gas serves as such alkali. A continuous .washing out ofthe ammonia by the wash liquor does not take place, of course, in thissulfureted hydrogen purification after the wash liquor has been oncesaturated With NH A further development of the methodrelates to aparticularly appropriate mode of operation for removing the sulfur fromthe alkali polysulfids formed in the hereinbetemperature of 90 to 100 U,at which temperature the alkali polysulfids dissociate and liberatesu'lfur. In this operation sulfureted hydrogen, or sulfureted hydrogenand ammonia are freed, whereas the sulfur sinks to the bottom in aflocculent readily separable form and can be separated from thesupernatent liquid by filtration and the like. This mode of operation isparticularly feasible and recommendable for gases containing cyanogen.In the method hereinbefore. referred to of sulfureted hydrogenpurification by means of an alkaline emulsion of metal oxid or ofhydrated ox-id and sulfur the process can be so conducted in thetreatment of gases containing cyanogen, that the cyanogen is removedfrom the gas and is taken up ,by an alkaline emulsion in the form ofsulfo-cyanogen compounds. The sulfo-cyanogen compounds are in such casedissolved as readily soluble compounds in the liquid and remain,afterthe separation of the liquid constituents from the solidconstituents in the liquid with the alkali polysulfids. x

If now we heat the liquid to the temperature at which the alkalipolysulfids dissociate with the separation of sulfur, we have at handthe means of recovering separately in the simplest manner thesulfo-cyanogen for the reason that it affords the possibility, evenWithin the field of coal distillation itself to transform thesesulfo-cyanogen compounds into ammonia and-thus to obtain a veryconsiderable increment of the output of ammonia. By this furtherdevelopment of the method we recover while simultaneously purifying thegases, the impurities heretofore diflicultly or not at all utilizable;sulfureted hydrogen and cyanogen, in the form of valuable commercialproducts (precipitated sulfur, sulfo-cyanogen compounds or ammonia) inthe continuous operation of coal distillation itself.

A further development of the invention consists in using again in theprocess the compounds. This is particularly economical vaporous productsof dissociation, sulfureted hydrogen or sulfureted hydrogen and Figure 2of the accompanying drawing) or by bringing the sulfureted-hydrogenvapors or the sulfureted hydrogen vapors and ammonia vapors into asecond apparatus and into contact with the mixture of iron and sulfurcompounds and sulfur (see Fig. 1).

This latter is .probably as a general rule preferable, because theconcentrated gases produce thereby a more hi hly concentrated solutionof alkali polysulfi s than is the case in the dilution of these gases bythe coal dis tillation gases.

As heretofore noted, the sulfureted hydrogen of the gases in thisprocess is recovere-l in the form of precipitated sulfur. Thesubject-matter of the invention contemplates further the combustion ofthis sulfur and the utilization of the S0, or SO gases thus produced forthe binding of the ammonia of the coal gases and the like. To this endthere may be conveniently employed the Burkheiser method of washing theS0 gases and the ammonia-containing distillation gases with a washliquor consisting of neutral and primary ammonium sulfite.

For the purpose of giving a diagrammatic representation of the process,I refer to the accompanying drawing, wherein- Fig. 1 indicates thesulfureted hydro en purification per 86, and Fig. 2, the sul uretedhydrogen purification and sulfur exin an alkaline emulsion, thentreating the resulting mixture of metallic sulfids and free sulfur withalkali sulfids for the purpose of removing the free sulfur, oxidizingthe residual metal sulfids to metal oxid (or hydrated oxid) and freesulfur and returning this mixture again into the purification process. 1

3. The process of removing sulfureted hydrogen from coal gas and thelike, which consists in employing for the absorption of the sulfuretedhydro en a mixture of metallic oxid (or hydrate oxid) and free sulfur inan alkaline emulsion, the alkali consisting of the ammonia of the gas.

4. The process of removing sulfuretcd by drogen from coal gasandthelike, which consists in employing for the absorption of stilfureted hydrogen a mixture of metallic oxid (or hydrated oxid) and freesulfur in an alkaline emulsion, and then, for the pur' pose of removingthe free sulfur, treating theresulting mixture with alkali sulfids,thereby oxidizing the residual metallic sulfids to metallic oxid orhydrated oxid and free sulfur and returning this mixture again into thepurification process.

5. The process of removing sulfureted hydrogen from coal gas and thelike, which consists inremploying for the absorption of the sulfuretedhydrogen a mixture of metallic oxid Sor hydrated oxid) and free sulfurin an a kaline emulsion, and then leaving'the resultant mixture of metalsulfid and free sulfur in contact with the sulfuretedhydrogen-containingas until the free sulfur present is disso ved by the alkali sulfidproduced.

6. The process of removing sulfureted hydrogen from coal gas and thelike, which consists in employing for the absorption of the sulfuretedhydrogen a mixture of metallic oxid (or hydrated oxid) and free sulfurin an alkaline emulsion, se arating from the resulting metallic sulfidst e liquid containing the alkali polysulfids and sulfocyanogen com oundsand heating the liquid until all oft e sulfur precipitates out as suchwhen the polysulfids decompose While any sulfa-cyanogen remain insolution, and restoring to the process the volatile dissociation roductsof the polysulfids (z'. e., sulfureted hydrogen and sulfureted hydrogenand ammoniacg.

7. The processof removing sulfurete hydrogen from coal gas and the like,which consists in employing for the absorption of the sulfuretedhydrogen a mixture of metallic oxid (or hydrated oxid) and freesulcompounds present fur in an alkaline emulsion, se crating from v theresulting metallic sulfids t e liquid containing the alkali polysulfidsand sulfocyanogen com ounds and heating the liquid until all of t esulfur precipitates out as such when the polysulfids decompose, Whileany sulfo-cyanogen compounds present remain in solution, and restoringto the process the volatile dissociation products of the polgsulfids (i.e., sulfureted hydrogen and sul ureted hydrogen and ammonia), saiddissociation products being admitted into the process before theentrance of the gas into the sulfureted hydrogen purification apparatus.

8. The process of removing sulfureted hydrogen from coal gas and thelike, which consists in employing for the absorption of are thesulfureted hydrogen a mixture of metallic oxid (or hydrated oxid) andfree sulfur in an alkaline emulsion, and then forming cyclic systems inone of which the metallic oxid and the metallic sulfid circulate and inthe other of which the dissolving medium and its component partscirculate, and bringing said cyclic systems to a common point of contactin a receptacle or apparatue serving as a sulfur diver. 6

' 9. The process of removing sulfureted hythe binding of the ammonia ofthe distilla- 1 drogen from coal gas and the like, which tion gases.consists in employing for the absorption of In testimony whereof I affixmy signathe sulfureted hydrogen a. mixturef of meture, in presence oftwo Witnesses. 5 tallic oxid (0r hydrated oxid) and ree sulfur in analkaline-emulsion, recovering free KARL BURKHEISER' sulfur from theresulting alkali polysulfids, Witnesses:

burning the said sulfur and utilizing the WILLY LENzz, S0 and S0 gasesthereby produced, for JOHANNES VoJs.

